The immune system has highly specialized cells for carrying out various processes; among them dendritic cells (DCs) have the ability to stimulate the primary and secondary responses of the B and T lymphocytes, as well as the response of T cytotoxic lymphocytes in rats and human lymphocytes (Carter et al., 2006). This capability is due to the fact that DCs are the cells that are most highly specialized in the presentation of antigens, internalizing, processing, and presenting them in the form of peptides combined with the molecules of the major histocompatibility complex class II (MHC-II). They originate from the myeloid progenitor cells, which are capable of differentiating themselves into immature dendritic cells and ultimately into mature dendritic cells by expressing various surface markers. The function as an antigen present or of dendritic cells has been connected to high levels in the expression of the DEC-205 receptor, also called CD205 or lymphocytic antigen 75, especially in dendritic cells located in areas of T cells of peripheral or secondary lymph organs (Jiang et al., 1995; Kraal et al., 1986; Winter-Pack et al., 1995). This was substantiated by the internalization of human anti-DEC-205 receptor dendritic cells (Bonifaz et al., 2002; Steinman and Banchereau, 2007; Steinman, 2008; Ueno et al., 2010). The DEC-205 receptor is an endocytic receptor with a broad extracellular domain that contains various subdomains: a cysteine-rich (CR) domain, a fibronectin type II (FN) domain and 10 contiguous carbohydrate recognition domains (CRDs), also known as C-type lectin domains (or CTLDs in the English acronym) (Mahnke et al., 2000). These multi-lectin domains affect the efficiency of the processing and presentation of antigens in vivo (Hawiger et al., 2001). Other examples of C-type lectin receptors include Langerina, DC-SIGN, mannose receptor and A2 phospholipase receptor, which have also been implicated in antigen processing and presentation (Figdor et al., 2002; Idoyaga et al., 2008).
It should be noted that the pioneering experiments that described the cellular processes of directing an antigen were carried out using the DEC-205 human receptor, where the T-cell-mediated response changes dramatically when the maturation stimulus of the dendritic cells is added at the same time as the directing of the antigen using an antibody directed against the DEC-205 receptor (Bonifaz et al., 2002; Hawiger et al., 2001). The proliferation of T cells increases by various orders of magnitude when compared to a classic immunization protocol. It has also been observed that, when the antigens are directed at the dendritic cells via DEC-205, there is an increase in the stimulation of the cooperating T cells (Th); this makes it possible or promotes the humoral immune response or antibody production (Bonifaz et al., 2004; Boscardin et al., 2006). In point of fact, the directing of antigens using this marker and CD11c has increased the kinetics of the production of high-titer antibodies during the first seven days after immunization (Wang et al., 2000; Cheong et al., 2010). Moreover, the presence of the DEC-205 receptor has been described in lines other than human dendritic cells, such as in B cells, T cells, NK cells, and monocytes (Kato et al., 2006); cerebral capillaries, stroma of the medulla ossea, and cortical epithelium of the thymus; they are also found in other species of mammals such as chimpanzees and rats and in other non-mammalian species (Kraal et al., 1986; Witmer-Pack et al., 1995), including chickens (Gallus gallus).
DEC-205 Receptor of Gallus gallus 
The genome and protein sequences for the DEC-205 receptor of Gallus gallus has been reported in the European Nucleotide Archive (http://www.ebi.ac.uk/ena/, access number AJ574899; in the ENSEMBL database (http://www.ensembl.org/), in the GenBank (http://www.ncbi.nlm.nih.gov), access number NP_001032925.1), and in the UniProtKB/TrEMBL, where it has access number Q4LDF5. These databases report the presence of 35 exons that have codifying sequences; these make up the domains of the DEC-205 receptor of chickens, represented as N-CRD-FNII-CTLD1-CTLD2-CTLD3-CTLD4-CTLD5-CTLD6-CTLD7-CTLD8-CTLD9-CTLD10-TMC, where N is the N-terminal region, CRD represents the cysteine-rich domain, FNII represents the type II fibronectin domain, CTLD1 to CTLD10 represent the 10 “type-C lectin domains”, and TMC represents the transmembrane and cytoplasmic domains (FIG. 1).
In recent years investigation into dendritic cells has been focused mainly on the application of new clinical procedures, in particular the implementation of new tools that enhance the immune response within short periods of time.
Antibodies
The use of antibodies or immunoglobulins that recognize the surface receptors of dendritic cells is based on the ability of these molecules to interact in a specific manner and with high affinity for the immunogens against which they are produced. The antigens are glycoproteins that comprise two heavy chains and two light chains that are interconnected by disulfide bridges to an antigen union region. The heavy chains have a variable region (VH) and a constant region (CH), with the latter being able to present 3-4 domains, which intervene directly in the union with cells of the immune system or with the complement system (Padlan, 1994). However, the light chains comprise a variable region (VL) and a constant region which has a single domain CL. The variable regions (VH and VL) contain the antigen union site, referred to as hypervariability regions or complementarity-determining regions (CDR). These regions are interspersed with more conservative regions that are called marker or “framework” regions (FR).
The antibodies that exhibit a high degree of union specificity and affinity for an epitope are the monoclonal antibodies, which are produced by a hybridoma that is generated by the fusion of immortalized cells (myeloma), which do not secrete immunoglobulins, and B cells obtained from the spleens of rats immunized against an antigen that contains the information of the heavy and light chains.
Combined with monoclonal interbody technology, in the state of the art, it is possible to obtain the genes that codify the variable domains of all possible immunoglobulins by rearranging the nucleotide sequences. This can be obtained from the lymphocytes of any vertebrate, including human beings. In reality, right now it is possible to select only the variable elements of the heavy and light chains of the antibodies, which can be united by a connector peptide in such a way as to produce a fragment of a single chain of the antibodies, which are able to recognize the antigens. Our group was able to prepare a bank of genes that express the single-chain fragments and, by means of the filamentous-phage deployment technique, it was possible to obtain antibodies that protect against toxins of scorpion venom (Riaño-Umbarilla et al., 2005, see also U.S. Pat. No. 7,381,802 B2, Jun. 3, 2008). An idea that underlies these advances in the technique and is complementary to this invention is to obtain single-chain fragments of human antibodies for the purpose of applying the same principle as described here, against possible antigens that cause health problems in humans (Rodriguez-Rodriguez et al., 2012). In other words, the idea is to obtain by genetic engineering the variability in single chains of human antibodies for possible application in the development of vaccines.